Human Rights Watch says indiscriminate Iraqi government airstrikes on cities have killed at least 75 civilians and wounded hundreds since early June.
The group says in a new report that Iraqi forces are dropping barrel bombs even as Baghdad denies using the deadly and destructive weapons.
Cities under attack have included the extremist held towns of Fallujah, Mosul, and Tikrit.
Human Rights Watch says the fight against a vicious insurgency is no license to kill civilians anywhere the military thinks extremists may be lurking.
It says Iraqi commanders who order explosives used in populated areas have committed war crimes and should be held accountable.
In Baghdad on Wednesday, the Iraqi parliament postponed a vote on choosing a new president of a power-sharing government by at least one more day.
U.N. special envoy to Iraq Nickolay Mladenov told the Security Council that Iraq cannot afford to drag out forming a new government. He said Iraq's very existence is under threat.
The Iraqi constitution calls for a Shi'ite prime minister, a Kurdish president, and a Sunni speaker of parliament. The lawmakers have been struggling, though, to agree on suitable candidates. So far, only a new speaker has been elected.